Pen



FIG. 1 is a front view of a pen showing my new design;

FIG. 2 is a left side view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is an enlarged top plan view thereof;

FIG. 6 is an enlarged bottom plan view thereof; and,

FIG. 7 is a perspective view thereof.

The broken lines in the drawings are included for the purpose of showing portions of the pen that form no part of the claimed design. 

CLAIM The ornamental design for a pen, as shown and described. 